The forecasters think La Nia will be a three-peat this year. This will be the third winter in a row that the Pacific Ocean has been in a La Nia cycle.
There is a new research from the University of Washington. Climate change is favored by La Nias in the short term according to a recent study.
The Pacific Ocean naturally cycles between El Nio and La Nia conditions, but our work suggests that climate change could be weighing the dice toward La Nia, said lead author Robert Jnglin Wills. We expect human-caused influences to reverse these trends and give El Nio the upper hand.
Predicting the direction of these long-term El Nio-like or La Nia climate trends is a goal of scientists.
Wills said that this is an important question over the next century for regions that are strongly influenced by El Nio.
The effects of El Nio and La Nia are wide-ranging. La Nia winters tend to be cooler and wetter in the Pacific Northwest and hotter and dryer in the Southwest. Dry conditions in East Africa are one of the global effects.
Knowing what to expect in the future can help communities prepare for weather in the future.
El Nios will be favored by global warming. Cold, deep water rising to the sea surface off South America will warm the air. The cooler ocean off South America will warm quicker than the warmer ocean off Asia because of the cooling effect of evaporation. This decreases the temperature difference across the tropical Pacific and lightens the surface winds blowing toward Indonesia, the same thing as happens during El Nio. Climate records show that the climate was more El Nio-like during warmer times.
While Earth's atmosphere has warmed in recent decades, the new study shows a surprising trend in the tropics. The authors looked at the temperatures at the surface of the ocean over the course of a decade. The Pacific Ocean off South America has cooled a bit. The western Pacific Ocean and eastern Indian Ocean have warmed more than the rest of the world. Climate models can't explain the two phenomena. This suggests that a missing process is to blame.
The temperature difference between the eastern and western Pacific has grown, surface winds have strengthened, and people are experiencing conditions typical of La Nia winters. There are temperature patterns at the ocean's surface. Thirty years of data isn't long enough to study the occurrence of El Nio and La Nia.
The climate models are still getting reasonable answers for the average warming, but there is something off about the pattern of warming in the tropics.
The researchers don't know why this pattern is occurring. Tropical climate processes and possible links to the ocean are explored by them. They might be able to predict when it will switch to El Nios once they know what is responsible.
If it turns out to be a natural long-term cycle, we may be able to expect it to switch in the next five to 10 years, but if it is a long-term trend due to some processes that aren't well represented in the climate models, then it would be Wills said that some mechanisms have a switch that will happen over the next few decades.
There was a study done before La Nia was announced. Wills isn't sure if he'll declare victory.
Wills said that the year-to-year changes are very unpredictable and it's important not to get too hung up on any individual year. In the next few years, I think we should watch for it.
The co-authors of the study are Kyle Armour and David Battisti at the University of Washington, as well as a researcher from the University of Illinois at Urbana-Champaign.
More information: Robert C. J. Wills et al, Systematic Climate Model Biases in the Large‐Scale Patterns of Recent Sea‐Surface Temperature and Sea‐Level Pressure Change, Geophysical Research Letters (2022). DOI: 10.1029/2022GL100011 Journal information: Geophysical Research Letters
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